I know the date on this post is old, but my experience. My aunt raised yorkies for some time. She did produce some chocolate yorkies, not intentionally. It was then found that the color mutation was consistant with a thyroid disorder. Please, please ...

First general question is why do you want to breed him? Other than that if he is a good representative of the breed he needs health clearances. You should be able to check with your breed club to find what goldens are prone to. Not my breed but proba...